This topic has been briefly touched in the introduction thread, with Simon commenting:

SimoRoth wrote:
I can't buy this game. If I did Maia would slip back about 14 months in development!

UPDATE: KSP is now availeble on Steam (here) (Windows, OSX or Linux!)
The demo has also been updated and is now on near-par with the full game.

It's about Rockets! Design/build them, and attempt to get them into orbit! Or land on one of the 4 other planets, or one of the many moons..
Or build your own Space Station, or a base! Anything!
The game uses an accurate (though slightly simplyfied) representation of a solar system in which you are free to launch rockets of any design.

Kerbals are an Alien race that recently discovered their place in a larger solar system, they are now highly motivated to conquer the Unknown. You are the director, designer, and pilot for their Aero-space program.

The game is still in early development (for example: there is no atmospheric-drag->heat system yet, you can plunge a bus-sized module through any atmosphere without it burning up).
There is no story line/career mode yet, for now its a huge sandbox rocket sim with infinite funds/parts.

The modding possibilities are huge, you can create custom parts, gauges, even entire game mechanics.
The original game does not have any life-support functionality, so someone created a life-support plugin. Plugins can all tie into each other easily so half a dozen others have created compatible tanks/solar panels to store/refresh the life-support system.
There is a large active community that shares designs, accomplisments, challenges etc..

[s]There is a free demo (v 0.13), it does not have a persistant game world yet (so you can only have 1 active mission at the time), and there is only 1 moon.
The (as of writing) most recent (paid) version (0.17) has EVA's, 4 more planets (with moons), more (and better balanced) parts, and loads of other improvements/additions.[/s]

I really want it, mainly because it reminds me so much of Spore, but I'm probably not going to get it. Mainly because it seems to have way too much depth for my measly little monkey-brain, and as a minor pet peeve it's not on Steam, and I've also heard (though not confirmed) that the devs hate Steam and/or refuse to put their game on Steam.

I'm good at whatever I apply myself to, I'm just not good at applying myself.

Fenrakk101 wrote:I really want it, mainly because it reminds me so much of Spore, but I'm probably not going to get it. Mainly because it seems to have way too much depth for my measly little monkey-brain, and as a minor pet peeve it's not on Steam, and I've also heard (though not confirmed) that the devs hate Steam and/or refuse to put their game on Steam.

You are making quite a lot assumptions...

a) Your measly little monkey-brain can most certainly take on this game. grab a capsule, a fuel tank and an engine. And voila you launch yourself into suborbital flight.
b) It's not on steam because the development method is incompatible (it's still in alpha, there is no complete game yet). On a side note: the devs love steam (and even if they didn't, everyone has his/hers likes and dislikes, why would such a thing withhold you from enjoying a game?)

Ortwin wrote:a) Your measly little monkey-brain can most certainly take on this game. grab a capsule, a fuel tank and an engine. And voila you launch yourself into suborbital flight.

Going farther requires a better understanding of physics. It requires more patience and knowledge of the physics of the game, and a better engineering intellect when it comes to designing the fuel-to-weight ratio, and even more knowledge when you mess around with the staging. I really enjoyed the Spore feel of it when I played the demo, but it felt like my own ability to comprehend the rules of the game was hindering my progress, which wasn't really fun for me, and I didn't want to look up guides for help because I would feel like I was copying other people's designs instead of creating my own. I'm weird, I know.

Ortwin wrote:b) It's not on steam because the development method is incompatible (it's still in alpha, there is no complete game yet). On a side note: the devs love steam (and even if they didn't, everyone has his/hers likes and dislikes, why would such a thing withhold you from enjoying a game?)

Thanks for clearing that up. I'd read some forums threads (on the KSP forums) where someone would ask to have the game on Steam and it would descend into a flame war with 80% of people saying Steam is the worst thing to happen. Maybe my Google skills are bad, but that kind of soured my impressions.
As for it impeding my enjoyment, there are a few different parts to it. I think the biggest part of it is that I just care way too much about politics for my own good (Part of my upbringing, I guess). Another part of it is that I currently have to manage accounts across Steam, GOG, Origin, Blizzard, Impulse, not including indie sites with individual registrations such as Minecraft. At some point I decided I had stretched myself too thin so I chose one of them and decided to focus on it to keep my brain from exploding, so now I like to manage all of my games through Steam so that I can spend more time gaming and less time fiddling with different accounts on different clients. Again, I'm weird, I know.

I'm good at whatever I apply myself to, I'm just not good at applying myself.

I really do enjoy this game, but it takes some time getting into if you are not familiar with how space travel works. Once you figure it out it's very fun and very impressive at times. They are working on making tutorials in the next version and the 2 currently working ones did a great job of teaching me how to orbit and land and how to control my ship once in space.

If you're looking for more gameplay in KSP, I do suggest a few mods. Mods are really easy to install just dragging and dropping folders pretty much. The 3 below are probably my favorites.

MechJab (Very handy Auto pilot and is pretty much the base plugin for most other mods, you can create your own autopilot for it to use as well.)RemoteTech (Lets you create satellite networks so you can use them to remotely control ships and debris)Protractor (Really handy tool so you don't have to do the math when it comes to interplanetary transfers. Great for new players that struggle with the math)

There is a ton of mods for this game a lot more than these 3 here. The game is still Alpha so right now it's a sandbox game similar to Garry's mod, Though I am sure this is one of those games that will be in an alpha / beta state for a long time .

Fenrakk101 wrote:
Going farther requires a better understanding of physics. It requires more patience and knowledge of the physics of the game, and a better engineering intellect when it comes to designing the fuel-to-weight ratio, and even more knowledge when you mess around with the staging. I really enjoyed the Spore feel of it when I played the demo, but it felt like my own ability to comprehend the rules of the game was hindering my progress, which wasn't really fun for me, and I didn't want to look up guides for help because I would feel like I was copying other people's designs instead of creating my own. I'm weird, I know.

Hmmm, the physics and F:W came kinda natural to me, but I know a few people who have NO talent for physics at all and still manage to design viable vessels.
Also, you are not required to reinvent the wheel, there is no shame in plundering wikipedia for orbital mechanics or to read a few proud 'look at my ship'-threads to inspire yourself for a different approach. My first mun-rocket was copied from a youtube vid, it had an HORRIBLE F:W, but it inspired my entire line Medium-heavy lifter rockets.
The deep knowledge is only required if you want to build perfect single-purpose intricate designs that are suiteble for only one thing. I recommend the 'be able to get 50 tons into orbit and from that point you can do anything' approach.

Thanks for clearing that up. I'd read some forums threads (on the KSP forums) where someone would ask to have the game on Steam and it would descend into a flame war with 80% of people saying Steam is the worst thing to happen. Maybe my Google skills are bad, but that kind of soured my impressions.
As for it impeding my enjoyment, there are a few different parts to it. I think the biggest part of it is that I just care way too much about politics for my own good (Part of my upbringing, I guess). Another part of it is that I currently have to manage accounts across Steam, GOG, Origin, Blizzard, Impulse, not including indie sites with individual registrations such as Minecraft. At some point I decided I had stretched myself too thin so I chose one of them and decided to focus on it to keep my brain from exploding, so now I like to manage all of my games through Steam so that I can spend more time gaming and less time fiddling with different accounts on different clients. Again, I'm weird, I know.

Forummites yelling != opinion of the developers, Steam is like iOS, apple, MS, car brands and sliced bread. Some prople sell their souls for it, others regard it as the Devil excrement flung around by monkeys.
Also, feel free to completely ignore the 'maintain account' 'obligation', every time I update/redownload KSP I have to request a passport reset. I'm not active at their forums at all, I just play the game (and check once a week how development is progressing, they have a good blog).
And you are not weird, just unique (like all of us).

Ortwin wrote:Forummites yelling != opinion of the developers, Steam is like iOS, apple, MS, car brands and sliced bread. Some prople sell their souls for it, others regard it as the Devil excrement flung around by monkeys.

My impression of it was that is 90% of the fanbase for the game would boycott it if it went to Steam, the devs would give in to majority rule. Not because that's what they want, but because that's what (it would appear) people wanted. I understand trolls have little influence in a game's development, but if almost nobody is telling you they want the game on Steam you might not be all that eager.

I'm good at whatever I apply myself to, I'm just not good at applying myself.